The Guru Photon R is a high-end race bike that combines a very light weight with an amazing degree of frame stiffness, and the resulting ride is fabulous.
If you're in the market for something fast and more than a little bit special – and you have the cash to back up your ambition – this is a bike that you need to check out. As for the rest of us, we can just dream.
If you're not familiar with Guru, it's a Canadian brand that has been around for the past 20 years, but you don't see too many of their bikes out on the roads of the UK. They're what you might call specialist.
Guru produce both custom and stock sized bikes in carbon fibre, titanium and steel. If you think of mass production, that's exactly what they aren't. Guru bikes are handmade in relatively small numbers in Guru's own facility in Montreal. The brand sees itself as pushing the boundaries in terms of materials and manufacturing techniques.
The Photon R is a lightweight carbon race machine that came to us via Cyclefit, the bike fit specialists based in Covent Garden, London.
There are three bikes in the Photon range. The Photon HL – the Hyperlight – has a claimed weight of under 670g for a 54cm frame – extraordinarily light. The SL – the Superlight – is under 750g, again for a 54cm frame. The Photon R – R for Race – doesn't quite match those on the scales, but it still weighs in at under 800g, so it's right up there (or down there) among the lightest of road bikes.
The Photon R is made from a mixture of high-modulus and standard-modulus carbon fibre and, as well as being light, the idea behind the choice of carbon and the lay-up design is that this bike is super-stiff for precise handling and efficient power transfer.
Although I didn't have a frame built especially for me, I went for a fit session at Cyclefit to get the setup right. This is a key part of the process with Cyclefit. They're all about getting you onto a bike that fits – the clue's in the name – in order to keep you comfortable, injury-free, and riding as efficiently as possible. The amount of expertise they have to offer is nuts and I can't recommend them highly enough. A bike fit by a skilled practitioner could be the best thing you've done since taking up cycling in the first place.
I've done two fit sessions with Cyclefit's Phil Cavell now, and they've both been really useful. Phil has adjusted all the key variables just a touch, taking into account a whole bunch of different factors: body dimensions, obviously, but also flexibility, how your feet move, your stability, past injuries, any limitations to your movement, and plenty more besides. It's a fascinating process. If you're skeptical, you'll be surprised.
Anyway, back to the bike itself. The sloping top tube is an almost square affair (with rounded off shoulders) that tapers along its length, and the down tube shares a similar blocky profile. Out back, the slim wishbone seatstays contrast with the deep and angular chainstays while the large and purposeful-looking bottom bracket shell houses a Press Fit BB.
Guru do the details well. The dropouts, for example, are full carbon, and although you can't see it, the tube junctions use a staggered carbon layup to avoid stress risers.
Our bike came built up with a full Shimano Ultegra Di2 groupset with the battery housed inside the seat post (it's compatible with a mechanical groupset too, with internal cable routing), Reynolds Assault wheels, and an aluminium handlebar, stem and seatpost from Ritchey. Phil fitted a Fizik Antares saddle for me after doing some pressure analysis of the way I sit and pedal. In that build, the bike (complete except for pedals) weighed 7.1kg (15.6lb).
If you go for a stock geometry (with the choice of custom paint options), you're looking at a price of £4,250 for the frame and forks. Go for a full custom geometry (with custom paint options) and that'll be £5,000. I did warn you that it was high end.
As we've said many times before, making a light frame is easy enough – just cut down on the amount of material you use. Making a stiff frame is easy enough if you don't mind how heavy it is. Making a frame that's both superlight and stiff, that's tough, but Guru have managed it with aplomb.
As Guru promise, the Photon R's overriding characteristic is its frame stiffness. It's not something you notice when you're just cruising along – most bikes can handle that just fine – but when you really give it the beans, the rigidity on offer here is excellent.
Whether you're getting out of the saddle for a steep climb or you're blazing it out in a full-on sprint, the bottom bracket doesn't drift. Guru say bottom bracket stiffness is 30% greater than that of the original Photon, although that tells you nothing if you haven't ridden one of those – and I'm guessing you haven't.
It's the same up front with the tapered (1 1/8in to 1 1/2in) head tube and Enve 2.0 fork. I'm a pretty big, long-limbed rider and I like to throw the bars about on the climbs, but the Photon R felt very, very solid through it all. I simply couldn't budge it off track when sprinting for signs. The only squish I could feel was the small amount you get as the tyres deform slightly when swinging the bike from side to side.
The other thing to bear in mind about that front end stiffness is the degree of cornering precision that it provides. You get your target in the crosshairs, you squeeze the trigger, and you hit every time. I could go on but that's it in a nutshell. You don't have to adapt to the margin of error because there's nothing to adapt to. Bang!
You can brake as hard and late as you dare and the fork ducks under very little despite its light weight (350g). Plus, if you go down the custom route you'll have a head tube length that's exactly right for you (with few or no headset spacers) and that will help with front-end solidity too. So, all in all, if you've not yet picked up the subtle hints, I'm saying that this frame is super-stiff.
All that stiffness means that the Guru is efficient but it lacks comfort, right? Well, that's actually not the case. Not even close, in fact. This is a very smooth riding bike that nullifies the vast majority of road buzz, handles bumps and holes just fine, and sticks to the road even when you're descending fast over knackered old Tarmac.
I had a lot of seatpost extending out of the frame, and the flex there was doubtless responsible for providing some of the damping (although it was a large 31.6mm diameter), and I also had that Fizik Antares saddle that Cyclefit recommended as a good option for me, but the ride quality of the frame is excellent – no question about it.
Guru reckon that they can engineer in the same ride quality whatever the size of the frame. Go for a custom model and they'll vary the frame composition according to your height and weight. That's the sort of thing you can get when you're spending this kind of wedge.
I won't go into the components too deeply because although this is one of Guru's standard builds, you can get the Photon R fitted with whatever you like through Cyclefit. The Shimano Ultegra Di2 groupset on our review bike worked as superbly as ever although, as mentioned before, if you're not into electronic shifting you can have a mechanical groupset instead. The one thing I'd certainly do, though, is swap the compact chainset for a standard option. The best choice there will come down to the individual, of course, but with a bike this light and responsive, the smaller chainrings left me feeling a little under-geared.
Overall, this is a simply superb race bike that boasts a stiffness-to-weight ratio that's right up there among the very best. With lightning-fast acceleration and exceptional climbing prowess, it's a force to be reckoned with in any company. The fact that it's comfortable enough that you can ride all day long and still feel fresh enough to fight it out in a sprint finish is the cherry on top.
High-end race bike that combines a light weight and an excellent level of frame stiffness, resulting in a superb performance.
road.cc test report
Make and model: Guru Photon R frame and fork
Size tested: n/a
About the bike
State the frame and fork material and method of construction. List the components used to build up the bike.
The frame is made by tube-to-tube construction, rather than coming out of a mould. Guru use a combination of high-modulus and intermediate-modulus carbon fibre.
Our review bike had:
Fork: Enve 2.0 full carbon
Groupset: Shimano Ultegra Di2
Wheels: Reynolds Assault
Handlebar: Ritchey WCS Pro Evocurve
Stem: Ritchey WCS 4-Axis
Seatpost: Ritchey WCS 1B
Saddle: Fizik Antares
Tell us what the bike is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about the bike?
Here's what Guru say:
"Engineered from the ground up to be incredibly stiff and light. The Photon R is the epitome of ultimate stiffness to weight.
"The Photon R delivers an aggressive feel without sacrificing the Photon's legendary ride quality. This frame was developed to surpass the stiffness numbers of industry leading frames, while reducing weight. We achieved this ambitious objective and exceeded it by creating an unparalleled race frame that weighs under 800 grams for a 54cm!
"Racers dream of a stiff frame that performs. The Photon R more than delivers with 30% increased stiffness in the bottom bracket region over the original Photon. Torsional stiffness jumps 30% for increased handling and precise cornering, while keeping the same figures in comfort and vertical compliance. Pedal harder and go further.
"Available in custom and our Fast Forward Race stock geometries, each Photon R is built using our proprietary ORE system (Optimum Ride Engineering) and a composite lay-up driven by the rider's height and weight. An expanded mix of high and standard modulus fibers are used to provide complete control of ride characteristics and uniformity. Whether you're 4'11' or 6'4' – you experience the same amazing ride!"
Guru deliver what they promise here: it's lightweight and rigid.
Frame and fork
Tell us about the build quality and finish of the frame and fork?
Excellent quality throughout.
Tell us about the materials used in the frame and fork?
They're both full-carbon, the frame being a combination of high-modulus and intermediate modulus carbon.
Tell us about the geometry of the frame and fork?
Go down the custom route and you can have whatever geometry you like.
Riding the bike
Was the bike comfortable to ride? Tell us how you felt about the ride quality.
I had a fit session so it was no surprise that the bike was set up right for me. The smoothness of the ride was more surprising.
How did the bike transfer power? Did it feel efficient?
Very efficient. That's the main characteristic of this bike, I'd say.
Wheels and tyres
Did you enjoy riding the bike? Very much.
Would you consider buying the bike? If only I had that sort of money!
Would you recommend the bike to a friend? Yes.
Anything further to say about the bike in conclusion?
The Guru Photon R puts in a stunning performance. If I was thinking of spending this kind of money, I'd almost certainly try to find the extra and go for a bespoke geometry – unless my ideal geometry was very, very close to a stock size.
The value mark is difficult. We're comparing this to other hand-made frames, not comparing it to frames out of a mould. You can get something maybe 80% or 90% as good for half the price, so it comes down to whether you're willing to pay extra for that final few percent.
About the tester
Age: 43 Height: 190cm Weight: 75kg
I usually ride: My best bike is:
I've been riding for: Over 20 years I ride: Most days I would class myself as: Expert
I regularly do the following types of riding: commuting, club rides, sportives, general fitness riding,
Mat has worked for loads of bike magazines over 20+ years, and been editor of 220 Triathlon and Cycling Plus. He's been road.cc technical editor for eight years, testing bikes, fettling the latest kit, and trying out the most up-to-the-minute clothing. We send him off around the world to get all the news from launches and shows too. He has won his category in Ironman UK 70.3 and finished on the podium in both marathons he has run. Mat is a Cambridge graduate who did a post-grad in magazine journalism, and he is a past winner of the Cycling Media Award for Specialist Online Writer.